International Association
for Cryptologic Research

This work describes a digital signature scheme constructed from a zero-knowledge proof of knowledge of a pre-image of the Rescue Prime Optimized (RPO) permutation. The proof of knowledge is constructed with the DEEP-ALI interactive oracle proof combined with the Ben-Sasson--Chiesa--Spooner (BCS) transformation in the random oracle model. The EUF-CMA security of the resulting signature scheme is established from the UC-friendly security properties of the BCS transformation and the pre-image hardness of the RPO permutation.

The implementation of the scheme computes signatures in 13 ms and verifies them in 1 ms on a single core when the BCS transform is implemented with the Blake3 hash function. (The multi-threaded implementation signs in 9.2 ms and also verifies in 1 ms.) These speeds are obtained with parameters achieving 122 bits of average-case security for \( 2^{122} \)-bounded adversaries with access to at most \( 2^{64} \) signatures.